The present invention relates to a control device for the drive of a reel or the like. The control is intended to maintain a constant or preset course of tension in the web of material to be wound up. European Patent Application 04 77 422 discloses one type of reel drive control device.
The Applicants have noted that upon the winding up of steel strips there results the problem that an increase in height results on the reel due to the clamping of the steel strip in the clamping slot. The increase in height leads to abruptly changing reel diameters upon the winding and unwinding of the strip. This abruptly changing reel diameter constitutes a deviation from a continuously developing diameter on which the setpoint input is based. The changes in diameter in turn cause deviations in the speed of the strip. As a result thereof, variations in the strip tension occur which in turn can lead to undesired defects in thickness.
The disturbance in the course of the tension is repeated periodically upon each revolution. Its frequency is thus a function of the rotational speed.